Articles
IMPROVING THE PROPERTIES OF POLYETHYLENE FILMS FOR AGRICULTURAL USES
Article number
434_24
Pages
205 – 212
Language
Abstract
Flexible polymeric films, particulary those made of polyethylene, have largely replaced glass as the leading greenhouse cover material.
The enormous versatility of the P E based films is due to the ability of plastic engineers in designing films with a multitude of porperties, tailor-made for a particular crop in particular conditions, through the use of additives and co-polymer in plastic blends.
Thermic additives transform an ordinarily "I" R transparent "P E films into a cover which induces the "greenhouse effect". Other additives prevent the accumulation of drops on the film surface, stabilizer prevent early photo-oxidative breakdown of films.
U V absorbers, light diffusers, pigments, shade additives, anti-dust and anti-static additives are all employed in today’s sophisticated films.
Advanced in the field of mulches have been no less dramatic.
The introduction in the 1980’s of new grades of polyethylene has made possible the wide use of extra-strong mulches as thin as 10–15 microns or less.
These can be made with a life span in the field over 12 months in regions with radiation exceeding 180 kilolangleys.
Specialy designed wave-length selective, multi-layered mulches are being used on a large scale to combat the ravages of the bemicia tabacci (whitefly), aphids and other pests.
Experiments are underway using herbicide-bearing mulches.
Specially designed thin mulches are used in solarization a non-chemical soil fumigation method.
The most exciting challenge today to the horticulturist and plastic developer is the use of selective, narrow-band blocking wave length films to intervene in the photomorphogenetic processes in order to induce hitherto unpredictable changes in plants behaviour.
This new field of research is waiting for the technology to be perfected.
The use of spectrophotometry is indispensible in the characterization of sophisticated films as well as in the quality assurance process.
The spectrograph, from which all of the optical properties can be deduced, should become a common instrument in the hands of the research workers, the extension officers as well as the farmer.
By demanding the graphs upon deciding on which film to purchase, the grower compels the producer of the films to raise the level of his hurdles.
The spectrographs change an anonymous piece of plastic into an implement having an "identification card".
The enormous versatility of the P E based films is due to the ability of plastic engineers in designing films with a multitude of porperties, tailor-made for a particular crop in particular conditions, through the use of additives and co-polymer in plastic blends.
Thermic additives transform an ordinarily "I" R transparent "P E films into a cover which induces the "greenhouse effect". Other additives prevent the accumulation of drops on the film surface, stabilizer prevent early photo-oxidative breakdown of films.
U V absorbers, light diffusers, pigments, shade additives, anti-dust and anti-static additives are all employed in today’s sophisticated films.
Advanced in the field of mulches have been no less dramatic.
The introduction in the 1980’s of new grades of polyethylene has made possible the wide use of extra-strong mulches as thin as 10–15 microns or less.
These can be made with a life span in the field over 12 months in regions with radiation exceeding 180 kilolangleys.
Specialy designed wave-length selective, multi-layered mulches are being used on a large scale to combat the ravages of the bemicia tabacci (whitefly), aphids and other pests.
Experiments are underway using herbicide-bearing mulches.
Specially designed thin mulches are used in solarization a non-chemical soil fumigation method.
The most exciting challenge today to the horticulturist and plastic developer is the use of selective, narrow-band blocking wave length films to intervene in the photomorphogenetic processes in order to induce hitherto unpredictable changes in plants behaviour.
This new field of research is waiting for the technology to be perfected.
The use of spectrophotometry is indispensible in the characterization of sophisticated films as well as in the quality assurance process.
The spectrograph, from which all of the optical properties can be deduced, should become a common instrument in the hands of the research workers, the extension officers as well as the farmer.
By demanding the graphs upon deciding on which film to purchase, the grower compels the producer of the films to raise the level of his hurdles.
The spectrographs change an anonymous piece of plastic into an implement having an "identification card".
Authors
Y. Ashkenazi
Keywords
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